Andy Murray dug deep to beat Spain's David Ferrer for the first time on clay and reach his third French Open semi-final.
The Briton, seeded third, won 7-6 (7-4) 6-2 5-7 6-1 and will face world number one Novak Djokovic in the last four.
Murray, 28, missed a match point in the third set but dominated the fourth to extend his unbeaten run on clay to 15 matches.
The victory takes him through to his 16th Grand Slam semi-final.
It looked as though Murray might have let the chance slip when a 3-0 lead and a match point went begging in the third set.
However, two fabulous backhand passes helped him reassert his dominance early in the fourth and the Scot wrapped up arguably his best clay-court win after three hours and 16 minutes.
"The third set was tough to lose having match point," said Murray. "The groundsman watered the court and I went to the bathroom to take a few minutes and get my composure back.
"It's going to be an extremely tough match against Novak. I'm going to need to play a high quality match to have a chance."
His quarter-final was very much the undercard at Roland Garros on a day when Djokovic was taking on nine-time champion Rafael Nadal on Court Philippe Chatrier.
The Scot had his own landmark to achieve on Court Suzanne Lenglen, however, as he targeted a first win in five attempts against clay-court expert Ferrer.
Murray was the more aggressive player, as expected, but also managed fewer unforced errors in a contest of punishing baseline exchanges.
The normally rock-solid Ferrer struggled with his serve, making 11 double faults and winning just 33% of points on second serve.
There were 13 breaks in total as two of the game's best returners traded blows, the first three games all going against serve.
Murray was broken to love in a poor game when he had the chance to serve out the set at 5-4, but took control of the tie-break after a woeful Ferrer volley.
The Scot reeled off 12 of 15 points as he moved 4-1 clear in the second, with Ferrer giving up his serve after an eighth double fault, and nine games out of 11 put Murray in command at 3-0 in the third.
Ferrer, 33, remains one of the best competitors in the sport though and fought his way back to level terms before saving a match point on serve at 5-4.
The Spaniard might have been unhappy with the courtside photographers, complaining to the umpire about their noise, but he broke again and served out the set to reignite his hopes.
Murray was under pressure and left the court to cool down, returning in superb form as he once again took the game to Ferrer and made his greater power tell.
A stunning cross-court pass gave him the immediate break in the fourth set, and he opened the next game with a copycat shot to grab the momentum and thrill the crowd.
There was no way back for Ferrer this time as Murray stormed into a 5-0 lead, and the Briton converted his third match point with a big serve followed by a fist pump in the direction of his team.
Novak Djokovic became only the second man to beat Rafael Nadal at the French Open with a straight-sets victory in the quarter-finals in Paris.
The world number one ended the nine-time champion's reign 7-5 6-3 6-1.
The Serb, now two wins from completing the career Grand Slam of all four major titles, will play Britain's Andy Murray in the semi-finals on Friday.
Nadal, on his 29th birthday, suffered his first defeat in six years and his second in 72 matches at Roland Garros.
"My tactic was to play aggressively and to stay focused on all points," said Djokovic.
"I have much respect for Rafa. He is obviously not playing at the level we expect from him this season,."
Nadal's only previous French Open loss came in the 2009 fourth round against Sweden's Robin Soderling - but this defeat was far less of a shock.
Djokovic, 28, went into the match as the favourite, on a 26-match winning streak and as a man on a mission, desperate to add the French Open to his Wimbledon, Australian and US Open victories.
The first set lasted a gripping 67 minutes as Djokovic raced into a 4-0 lead after 21 minutes only for Nadal, constantly urging himself on, to haul himself back to 4-4.
Top seed Djokovic pressed hard once again to earn three set points in a 12-minute 10th game, but had to wait until the 12th to make the decisive move.
Nadal missed a routine smash, reminiscent of the overhead Djokovic failed to put away in their epic semi-final two years ago, and eventually succumbed on the sixth break point with a volley into the tram lines.
The Spaniard held on in the early stages of the second set but Djokovic was now giving him far fewer chances as he tightened up his serve, and the pressure told.
Nadal went wide on break point to fall 5-3 behind and Djokovic calmly served out for a two-set lead.
In the end, the crowd on Court Philippe Chatrier that has watched Nadal dominate for a decade was left giving him sympathetic applause as he managed to avoid a third-set drubbing.
The Majorcan finally got on the scoreboard at 4-0 down but by now his second serve was being routinely despatched by the Serb.
Nadal could do nothing to combat the barrage of returns and gave up his crown with a double fault after two hours and 26 minutes.
There were no excuses from Nadal afterwards.
"He was better than me. That's it. It's very simple," he said.
"When one opponent is playing better than you and is in better shape than you, that can happen."